IFR Lost Communications: A Pilot's Complete Guide to 14 CFR 91.185

What does 14 CFR 91.185 actually say?

14 CFR 91.185 is the governing regulation for every IFR two-way radio communications failure. Its three subsections establish when the rule applies, what to do in VFR conditions, and the full procedure for IMC conditions. The regulation opens: "Unless otherwise authorized by ATC, each pilot who has two-way radio communications failure when operating under IFR shall comply with the rules of this section."

The structure is deliberately hierarchical. The VMC rule in 91.185(b) is the simplest and most preferable outcome. The IMC rule in 91.185(c) fills in only when VMC flight is unavailable or insufficient. Within 91.185(c), the route, altitude, and timing rules each carry their own internal hierarchy — ordered so that ATC's most recent specific instructions take precedence over older or more general ones. Understanding that logic is the foundation for answering any DPE scenario correctly, because no two lost-comm scenarios are identical.

What do you do if you lose communications in VMC — 14 CFR 91.185(b)?

14 CFR 91.185(b) states: "If the failure occurs in VFR conditions, or if VFR conditions are encountered after the failure, each pilot shall continue the flight under VFR and land as soon as practicable." The phrase "as soon as practicable" means the nearest suitable airport where you can land safely — not necessarily the originally planned destination, and not necessarily immediately if doing so would create a hazard.

Squawk 7600 immediately regardless of VMC or IMC conditions. ATC will see the code and begin clearing airspace. At a towered airport, monitor the tower frequency and watch for light gun signals — ATC may clear you to land via a steady green light. At a non-towered airport, overfly to observe traffic pattern direction and land normally. Notify ATC of the malfunction as soon as possible after landing per 14 CFR 91.187.

What is the IMC lost-comm procedure under 14 CFR 91.185(c)?

14 CFR 91.185(c) states: "If the failure occurs in IFR conditions, or if paragraph (b) of this section cannot be complied with, each pilot shall continue the flight according to the following" — then prescribes three separate rules for route, altitude, and leaving the clearance limit. Each rule has its own internal priority order.

The 91.185(c) IMC procedure applies in two situations: (1) the failure happens while you are already in IMC, or (2) the failure happens while you are in VMC but VFR flight is not possible — for example, the terrain or airspace makes descending to remain VFR impractical, or doing so would require leaving the IFR environment in a way that creates greater risk. "Cannot be complied with" is a pilot judgment call and DPEs will probe that reasoning.

What route do you fly — the AVE-F hierarchy?

14 CFR 91.185(c)(1) establishes four route options in descending priority:

The vectored case (V) deserves close attention. If you lose comms while being radar vectored — common during an approach — you do not fly the heading you were on indefinitely. The regulation instructs you to fly direct from the point of radio failure to the fix, route, or airway that was named in the vector clearance. That fix is your target; navigate direct to it and resume the cleared route from there.

The "Expected" option (E) captures a common ATC habit: controllers often give pilots a heads-up about what their next clearance will be. "Expect direct BOSCO at 1530Z" or "Expect the ILS 28L at KORD" — these advisory statements activate the E leg of AVE-F if you lose comms before receiving the actual clearance. Pilots who don't write down their expected routing lose this option and fall back to Filed.

What altitude do you fly — the MEA hierarchy?

14 CFR 91.185(c)(2) requires flying "the highest of the following altitudes or flight levels for the route segment being flown":

Unlike the route rule, which is a sequential priority chain (use A unless unavailable, then V, then E, then F), the altitude rule is a comparison: evaluate all three altitudes that apply to your current segment and fly the numerically highest one. The common memory aid is MEA — not as a sequence but as a checklist of the three values to compare.

A critical nuance: the altitude rule applies "for the route segment being flown." If your route crosses multiple airway segments with different MEAs, you must recompute the comparison at each segment boundary. You may need to climb from your assigned altitude to the MEA on a segment where the MEA is higher, then descend back to the MEA on a lower segment — unless the expected or assigned altitude is higher than that lower MEA.

At FL180 and above, 14 CFR 91.121(c) requires converting MEAs to minimum flight levels using the standard pressure setting of 29.92 in. Hg. The regulation cross-references this explicitly in 91.185(c)(2)(ii).

When do you leave the clearance limit and begin your approach?

14 CFR 91.185(c)(3) governs timing for leaving your clearance limit and commencing an approach. The rule branches on whether your clearance limit is a fix from which an approach begins (an IAF or approach fix) or not.

1. 1
   Case 1: Clearance limit IS a fix from which an approach begins

   Descend to begin the approach as close as possible to the expect-further-clearance (EFC) time if one was received, OR as close as possible to the estimated time of arrival (ETA) calculated from your filed or amended estimated time en route — if no EFC was received.
2. 2
   Case 2: Clearance limit is NOT a fix from which an approach begins

   Leave the clearance limit at the EFC time if received, OR upon arrival at the clearance limit if no EFC was received. Then proceed to a fix from which an approach begins and descend as close as possible to the ETA calculated from filed or amended estimated time en route.

The practical implication of Case 1: if ATC cleared you to an IAF and gave you an EFC of 1445Z, hold at the IAF until 1445Z (or as close to it as your hold timing allows), then begin the approach. If no EFC was given, compute your own ETA from departure using your filed estimated time en route and use that as your target for starting the approach.

The practical implication of Case 2: if you were cleared to a waypoint that is not an approach fix — a fix used only for airspace organization, like a holding pattern entry fix — depart that fix at the EFC time (or immediately upon arrival if no EFC), navigate to the nearest IAF, then begin the approach as close as possible to your ETA.

Both cases share the same underlying logic: ATC needs to predict when you will appear on the approach course so they can protect the arrival sequence. The EFC and ETA are the coordination tools that make that prediction possible.

What communication actions should you take immediately?

Before resigning yourself to the full lost-comm procedure, try every available means to restore communications. The AIM Section 6-4-1 instructs pilots to attempt communications on all available frequencies, including previously assigned frequencies, 121.5 MHz (the emergency frequency monitored by most ATC facilities and many aircraft), and any frequency published on the applicable chart or in the Airport/Facility Directory.

• Squawk 7600 immediately — this is your highest-priority action and alerts every ATC facility tracking you
• Transmit in the blind on your last assigned frequency — state your position, intentions, and that you are experiencing communications failure
• Transmit in the blind on 121.5 MHz — monitored by most ATC facilities, airlines, and military aircraft
• Try the published approach control, center, or ATIS frequency for the destination
• Try your departure frequency if you have not been handed off — the original controller may still have you in radar contact
• Use a cell phone or satellite communicator if available and safe to do so — ATC facilities have published phone numbers and many can relay instructions through other aircraft
• Monitor the destination ATIS — if ATC is aware of your situation they may embed instructions in the ATIS broadcast
• Watch for light gun signals on approach — ATC will attempt to communicate via light gun if they identify a 7600 transponder inbound

Transmitting in the blind is not futile. Other aircraft on frequency may hear you and relay your position to ATC. Airlines routinely relay lost-comm reports. Your call confirms your intentions and gives ATC additional data to build their prediction model.

What must you report after the flight — 14 CFR 91.187?

14 CFR 91.187(a) states: "The pilot in command of each aircraft operated in controlled airspace under IFR shall report as soon as practical to ATC any malfunctions of navigational, approach, or communication equipment occurring in flight." This is not optional and not limited to total failures — partial degradation of IFR capability must also be reported.

The report under 91.187(b) must include four elements:

• Aircraft identification
• Equipment affected
• Degree to which the capability of the pilot to operate under IFR in the ATC system is impaired
• Nature and extent of assistance desired from ATC

File the report as soon as you re-establish communication with any ATC facility — which may be immediately upon landing at a towered airport. At a non-towered airport, contact the nearest FSS or ARTCC by phone. The requirement persists; the 91.187 obligation does not expire when the flight ends.

What does ATC do when they identify a lost-comm aircraft?

When ATC receives a 7600 squawk, they initiate a lost communications protocol designed to work in concert with the 91.185 procedure. Understanding ATC's side of the event helps you recognize why the 91.185 rules are written the way they are.

• The radar facility notifies all downstream facilities along the expected route — approach control, center, tower — so each facility can prepare
• ATC clears a corridor along the AVE-F route at the altitude the aircraft is expected to fly per the MEA hierarchy
• Traffic conflicting with the lost-comm aircraft's expected path is re-sequenced or held
• The destination approach control sequences the lost-comm aircraft into the arrival flow at the estimated approach time (ETA from 91.185(c)(3))
• Tower personnel at the destination are alerted to issue light gun signals and watch for the aircraft
• If the aircraft arrives and the tower cannot establish visual contact, the approach sequence is held clear until the ETA window passes

This coordination is why the EFC and ETA rules in 91.185(c)(3) are precise: ATC is building a mental model of where you will be and when. Every deviation from the published procedure — flying a different altitude, taking a shortcut, or starting the approach early — breaks that model and can create a collision hazard with traffic ATC has sequenced around your predicted path.

Worked scenarios — applying 91.185 to real situations

Scenario 1: VMC failure on departure

You depart KBOS IFR, cleared to KBDL via the RUUTH2 departure, then direct COPES, then Victor 3. At 4,000 feet in VMC you lose your comm radio. The MEA on Victor 3 is 3,000 feet. Your assigned altitude is 6,000 feet.

Rule: 91.185(b) applies — you are in VMC. Squawk 7600, continue VFR, and land as soon as practicable. You do not need to execute the full IMC procedure. Choose the nearest suitable airport and land. Notify ATC of the malfunction after landing per 91.187.

Scenario 2: Simple IMC failure enroute

You are IFR, IMC, cleared direct BOSCO then Victor 23 to KORD. Assigned altitude 9,000 feet. The MEA on Victor 23 is 8,000 feet. You received "expect 11,000 feet in 20 minutes" before losing comms.

Route (AVE-F): Assigned — fly direct BOSCO then Victor 23 as cleared. No vector in progress, so V does not apply. A is your answer.

Altitude (MEA hierarchy): Compare all three. MEA = 8,000 feet. Expected = 11,000 feet. Assigned = 9,000 feet. Highest = 11,000 feet. Climb to 11,000 feet and maintain for this segment.

Result: Fly the assigned route at 11,000 feet.

Scenario 3: Radar vector failure during approach

You are being vectored to the ILS 10L at KORD. The last vector clearance was: "Turn left heading 270, vectors to the ILS 10L final, expect KECHI as the final approach fix." You lose comms on the heading 270 vector, currently in IMC.

Route (AVE-F): You were being radar vectored when comms failed (V applies). Fly direct from your present position to KECHI (the fix named in the vector clearance) and intercept the ILS 10L course. Do not continue heading 270 indefinitely.

Altitude: Maintain the last assigned altitude until established on the approach, then follow published approach altitudes. The ILS glideslope takes over once intercepted — but do not descend below the last assigned altitude until you have intercepted the glideslope and are established.

Timing: Begin the approach as close as possible to your EFC time if received, or your ETA if not. Squawk 7600 and watch for light gun signals from the tower.

Common DPE oral questions on IFR lost communications

DPEs are required by the Instrument Rating ACS to evaluate Task IR.VII.A — Emergency Operations: Loss of Communications. Expect the DPE to build a specific scenario around your proposed flight and probe every element of 91.185 within that context.

• "You lose comms in VMC — what do you do?" (91.185(b): continue VFR, land as soon as practicable)
• "You lose comms in IMC — walk me through your route decision." (AVE-F hierarchy; must identify which option applies to the specific clearance just discussed)
• "What altitude do you fly on this segment?" (name all three MEA/Expected/Assigned values, identify the highest)
• "You were being vectored when you lost comms — now what?" (fly direct to the named fix in the vector clearance)
• "Your clearance limit is an IAF and you have an EFC of 1430Z — when do you start the approach?" (as close as possible to 1430Z)
• "You have no EFC and your clearance limit is not an approach fix — when do you leave?" (upon arrival, then proceed to the approach fix, begin approach as close as possible to ETA)
• "What transponder code do you set?" (7600 immediately)
• "After you land, what do you report and to whom?" (91.187 malfunction report: aircraft ID, equipment affected, degree of impairment, assistance desired)
• "What frequencies do you try before accepting that comms are truly lost?" (last assigned, 121.5, destination approach, any published frequency — transmit in the blind on each)

What does AIM 6-4-1 add to the 91.185 procedure?

AIM Section 6-4-1 (Two-Way Radio Communications Failure) provides operational guidance that complements — but does not supersede — the regulatory requirements in 91.185. The AIM is not regulation, but DPEs expect candidates to know its guidance as a practical supplement.

Key AIM 6-4-1 points that go beyond the bare regulation text include:

• Attempting all available frequencies before declaring the failure unresolvable — including 121.5 MHz and any previously assigned frequencies
• Transmitting in the blind: stating position, altitude, and intentions on the last assigned frequency and 121.5 MHz, so other aircraft or ATC facilities can relay
• Confirming that ATC will attempt to communicate via light gun signals at the destination airport once the aircraft is identified inbound on 7600
• Noting that if the pilot receives a clearance via relay (through another aircraft) before reaching the clearance limit, the relay clearance supersedes the lost-comm procedure
• Advising that VFR-on-top is one option for complying with 91.185(b) in appropriate conditions — maintaining VFR while continuing IFR flight rules is permissible if conditions allow

The AIM's core message mirrors the regulatory intent: the lost-comm procedures exist to make your behavior predictable to ATC. Every action you take — route, altitude, timing — should be one that ATC can anticipate by knowing the 91.185 rules and your filed flight plan.

Frequently Asked Questions

Sources

This article was researched from FAA primary sources (14 CFR 91.185, 14 CFR 91.187, AIM Section 6-4-1, Instrument Rating ACS, Instrument Procedures Handbook) and citing current Cornell LII regulation text — drafted by MockDPE. Last updated: May 2026. If you spot an inaccuracy, email corrections@mockdpe.org.